Various methods can be used to establish or verify the identity and authority of an individual. For example, people use physical badges to identify themselves and establish their authority or permissions in a variety of contexts. For example, a person may present an employee badge to gain access to an employer's secure building.
Paper documents can be signed to associate a person with the document in a reasonably verifiable manner. The document may have different significance or meaning depending on the identity and authority of a person who signs the document.